Imaging module and catheter with flexible wiring substrate

ABSTRACT

An imaging module includes an electrical cable; a solid-state imaging element having an imaging unit orthogonal to an axis direction of a tip of the electrical cable; and a flexible wiring substrate in which the solid-state imaging element and the electrical cables are electrically connected together. The flexible wiring substrate includes an element mounting portion mounting the solid-state imaging element, and two rear pieces that are bent at both end portions of the element mounting portion and extend in a direction away from the element mounting portion. An internal space of the flexible wiring substrate surrounded by the element mounting portion and the two rear pieces is filled with adhesive resin in which a glass-transition temperature is 135° C. or less.

CROSS REFERENCE TO RELATED APPLICATIONS

Priority is claimed on Japanese Patent Application No. 2015-080227,filed on Apr. 9, 2015, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an imaging module in which asolid-state imaging element is connected to an electrical cable via aflexible wiring substrate, and a catheter configured using the imagingmodule.

Description of Related Art

A lot of imaging modules in which an imaging unit having a solid-stateimaging element is assembled to the tip of an electrical cable areadopted for catheters.

The imaging modules have, for example, a configuration in which aflexible wiring substrate (FPC) having a solid-state imaging elementmounted thereon and an objective lens unit are housed within a tubularmetal frame member and the solid-state imaging element is electricallyconnected to an electrical cable via the flexible wiring substrate.

In an imaging element shown in Japanese Unexamined Patent Application,First Publication No. 201.1-217887, a flexible wiring board (FPC) havingan imaging element chip (solid-state imaging element) mounted at acentral portion thereof is electrically connected to a signal cable. Thewiring board is bent to a side opposite to the imaging element chip atboth ends in a location where the imaging element chip is mounted, and ablock for supporting and guiding the wiring board is provided in a spacesurrounded by a central portion and an extension portion of the wiringboard.

In an imaging module shown in Japanese Unexamined Patent Application,First Publication No. 2013-214815, a flexible wiring substrate (FPC)having a solid-state imaging element at a central portion thereof isconnected to an electrical cable. The flexible wiring substrate is bentto a side opposite to the solid-state imaging element, and an internalspace surrounded by the element mounting portion and a rear piece isfilled with resin that supports the flexible wiring substrate.

In the imaging element shown in Japanese Unexamined Patent Application,First Publication No. 2011-217887, it is necessary to fix the extensionportion of the wiring board to the block in order for it to be connectedto the signal cable, and it is difficult to reduce the diameter thereofdue to the presence of the block. For example, it is difficult to setthe outside dimension of the imaging module portion to 2 mm or less.Additionally, there is concern that the wiring board may be disconnecteddue to warpage caused by a difference in coefficient of thermalexpansion from that of the block.

In the imaging module shown in Japanese Unexamined Patent Application,First Publication No. 2013-214815, it is difficult to make a diametersmall without causing disconnection in the bent portion of the flexiblewiring substrate.

SUMMARY

The present invention has been made in view of the above-describedcircumstances, and provides an imaging module and a catheter that canmake a diameter small without impairing connection reliability.

A first aspect of the present invention is an imaging module includingan electrical cable; a solid-state imaging element having an imagingunit orthogonal to an axis direction of a tip of the electrical cable;and a flexible wiring substrate in which the solid-state imaging elementand the electrical cables are electrically connected together. Theflexible wiring substrate includes an element mounting portion mountingthe solid-state imaging element, and two rear pieces that are bent atboth end portions of the element mounting portion and extend in adirection moving away from the element mounting portion. An internalspace of the flexible wiring substrate surrounded by the elementmounting portion and the two rear pieces is filled with adhesive resinin which a glass-transition temperature is 135° C. or less.

In a second aspect of the present invention according to the imagingmodule of the first aspect described above, it is preferable that therear pieces have extending portions configured so that portions, whichinclude at least extending ends, approach each other as the extendingportions are away from the element mounting portion, and connectingpieces further extending from the extending ends, and the internal spacebe surrounded by the element mounting portion and the extendingportions.

In a third aspect of the present invention according to the imagingmodule of the first aspect or the second aspect described above, it ispreferable that the outside dimensions of the flexible wiring substrateincluding the element mounting portion and the two rear pieces, whichcover the adhesive resin, be equal to or less than the outsidedimensions of the solid-state imaging element.

In a fourth aspect of the present invention according to the imagingmodule of any one of the first to the third aspects described above, itis preferable that the adhesive resin be an acrylic resin or anepoxy-based resin.

In a fifth aspect of the present invention according to the imagingmodule of the second aspect described above, it is preferable that theadhesive resin have intermediate corners between first, second corners,which are formed between the element mounting portion and the twoextending portions, and a third corner formed in a place where the twoextending portions meet, respectively, and be formed in a polygonalshape having five or more sides as a whole.

In a sixth aspect of the present invention according to the imagingmodule of any one of the first to the fifth aspects described above, itis preferable that a rate of volumetric shrinkage in curing of theadhesive resin be 3% or more.

A seventh aspect of the present invention is a catheter including animaging module of any one of the first to the sixth aspects describedabove.

According to the aspects of the present invention described above, aninternal space of the flexible wiring substrate surrounded by theelement mounting portion and the two rear pieces is filled with adhesiveresin in which a glass-transition temperature is 135° C. or less.Therefore, the adhesive resin can be softened when being put in ahigh-temperature state (for example, 135° C. or more) in sterilizationprocessing using an autoclave. Accordingly, a situation in which a largeforce is applied to the bent portion or the like of the flexible wiringsubstrate can be avoided even in a high-temperature state, and damage ofthe flexible wiring substrate can be prevented. As a result, connectionreliability can be improved.

According to the aspects of the present invention described above, sinceno large force is applied to the flexible wiring substrate by adhesiveresin, an excessive force is not applied to the bent portion even if theoutside dimensions of the flexible wiring substrate surrounding theadhesive resin are made small. Hence, the diameter of the imaging modulecan be reduced by adjusting the shape of the flexible wiring substratesurrounding the adhesive resin.

Additionally, according to the aspects of the present inventiondescribed above, since a configuration is provided in which the internalspace of the flexible wiring substrate is filled with the adhesiveresin, a member for maintaining the shape of the flexible wiringsubstrate is unnecessary, and disconnection of the flexible wiringsubstrate caused by a difference in coefficient of thermal expansionfrom that of the member does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an imaging module related to anembodiment of the present invention and a tip structure of a catheterassembled using the imaging module.

FIG. 2A is a sectional view showing a portion of a tip portion of theimaging module.

FIG. 2B is a view showing adhesive resin.

FIG. 3 is a view showing dimensions in the tip portion of the imagingmodule.

FIG. 4A shows a modification example of the adhesive resin with whichthe imaging module is filled, and shows an example in which angels θ1and θ5 of corners r1 and r5 are made larger than 90°.

FIG. 4B shows a modification example of the adhesive resin with whichthe imaging module is filled, and shows an example in which the adhesiveresin is a polygon of more than five sides.

FIG. 4C shows a modification example of the adhesive resin with whichthe imaging module is filled, and shows an example in which the sidesbetween corners r1 and r5 and a corner r3 of the adhesive resin areformed in a curved convex shape.

FIG. 5 is a sectional view showing a portion of a tip portion of anotherexample of the imaging module.

FIG. 6A is a view showing a process of manufacturing the imaging moduleof the present invention.

FIG. 6B is a view showing a process of manufacturing the imaging moduleof the present invention.

FIG. 6C is a view showing a process of manufacturing the imaging moduleof the present invention.

FIG. 6D is a view showing a process of manufacturing the imaging moduleof the present invention.

FIG. 6E is a view showing a process of manufacturing the imaging moduleof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is described with reference toFIGS. 1 to 6E. In the following description, in FIG. 1, a left endportion, that is, a solid-state imaging element 4 side with respect to aflexible wiring substrate 10 is referred to as a front portion, and aright end portion opposite (right side in FIG. 1) to the left endportion is referred to as a rear portion. FIGS. 1 to 6E are views asseen from a direction perpendicular to a forward-rearward direction anda longitudinal direction D1 (to be described below).

FIG. 1 shows an imaging module 100 of the embodiment related to thepresent invention and a tip structure of a catheter 101 assembled usingthe imaging module 100. FIG. 2A is a sectional view showing a portion ofa tip portion of the imaging module, and FIG. 2B is a view showing anadhesive resin.

The imaging module 100 is configured by electrically connecting andattaching a flexible wiring substrate 10 (FPC), on which the solid-stateimaging element 4 having an imaging unit 3 is mounted, to the tip of aconductor 2 of an electrical cable 1. As the solid-state imaging element4, for example, a complementary metal oxide semiconductor (CMOS) can besuitably used.

The imaging module 100 is configured such that the solid-state imagingelement 4 is electrically connected to the electrical cable 1 via theflexible wiring substrate 10.

The flexible wiring substrate 10, as shown in FIG. 2A, has an elementmounting portion 11 in which the solid-state imaging element 4 ismounted on the front portion of a mounting surface 11 a, and two rearpieces 12 and 13 that are bent at both end portions of the elementmounting portion 11 and extends to the rear portion.

As the flexible wiring substrate 10 is bent at both the end portions ofthe element mounting portion 11 and is made to extend to the rearportion, the two rear pieces 12 and 13 are formed.

The flexible wiring substrate 10 is, for example, a single-sided wiringtype flexible wiring substrate. That is, the flexible wiring substrate10, as shown in FIG. 2A, has a structure in which wiring 14 formed onone surface side of an insulated base material 10 a with electricinsulation formed in the shape of a film is covered with a resist film10 b (a covering layer, for example, solder resist) with electricalinsulation. The insulated base material 10 a is made of, for example,polyimide, and the wiring 14 is made of, for example, copper.

A mounting part back surface 11 b is a surface opposite to the mountingsurface 11 a of the element mounting portion 11.

As shown in FIG. 1, outside surfaces 12 b and 13 b (outer surface) ofthe rear pieces 12 and 13 are respectively provided with pad-liketerminal portions 12 c, 12 d, 13 c, and 13 d for a conductor, An innerconductor 2 a and an outer conductor 2 b of the conductor 2 that is ledout from a jacket 5 of the electrical cable 1 are electrically connectedto the terminal portions 12 c, 12 d, 13 c, and 13 d for a conductor,respectively.

In electrical cable 1, a cable unit is configured by a plurality of theconductors 2 being collectively covered with the jacket 5.

The conductor 2 has the inner conductor 2 a, a primary covering layer 2c that covers the inner conductor 2 a, an outer conductor 2 b that isformed in a net-like fashion of thin metallic wires and is providedaround the primary covering layer 2 c, and a secondary covering layer 2d that covers the outer conductor 2 b.

As shown in FIGS. 1 and 2A, the imaging unit 3 is electrically connectedto the wiring 14 of the flexible wiring substrate 10 via an electriccircuit formed in the solid-state imaging element 4.

The solid-state imaging element 4 has a bump 4 a, electrically connectedthe electric circuit of the solid-state imaging element 4, on a backsurface thereof opposite to a surface on which the imaging unit 3 ismounted. The bump 4 a is, for example, a solder bump, a stud bump, aplating bump, or the like.

The solid-state imaging element 4 is of a flip chip type, and iselectrically connected to the wiring 14 of the flexible wiring substrate10 by joining and fixing the bump 4 a to an electrode portion (notshown) formed on the mounting surface 11 a of the element mountingportion 11 of the flexible wiring substrate 10.

The element mounting portion 11 of the flexible w ng substrate 10 iselectrically connected to the respective terminals 12 c, 12 d, 13 c, and13 d which are for a conductor via the wiring 14 of the flexible wiringsubstrate 10. Accordingly, the electric circuit of the solid-stateimaging element 4 and the conductor 2 of the electrical cable 1 areelectrically connected together via the wiring 14.

The entire rear pieces 12 and 13 of the flexible wiring substrate 10 inthe imaging module 100 are covered with an insulating tube 15 havingelectric insulation.

The insulating tube 15 is, for example, a tubular member made ofsilicone resin, and is suitable in that the insulating tube can besmoothly and slidingly moved at low friction with respect to theconductor 2 of the electrical cable 1 or the flexible wiring substrate10.

The insulating tube 15 is fixed to and integrated with the internalflexible wiring substrate 10 and the conductor 2 with inner layer resin16 that fills the inside of the insulating tube and is cured.

A conductor connecting portion 17 a obtained by soldering the conductor2 a of the conductor 2 to the terminals 12 c and 13 c for a conductorand a conductor connecting portion 17 b obtained by soldering theconductor 2 b of the conductor 2 to the terminals 12 d and 13 d for aconductor are respectively formed in the rear pieces 12 and 13 of theflexible wiring substrate 10.

In the imaging module 100, the catheter 101 is configured by furthermounting a lens unit 20 and an outer frame member 21

The lens unit 20 is attached to a light-receiving surface 3 a of eimaging unit 3 via a transparent cover member 22.

The outer frame member 21 is a member having, for example, a cylindricalshape or the like, which houses a tip of the imaging module 100 togetherwith the cover member 22 and the lens unit 20 that are fixed to thesolid-state imaging element 4.

The lens unit 20 is obtained by incorporating an objective lens (notshown) into a cylindrical lens barrel 20 a, and is provided by aligningan optical axis with the light-receiving surface 3 a of the imaging unit3 and fixing one end of the lens barrel 20 a in an axis direction to thecover member 22.

The lens unit 20 focuses the light, which is guided via a lens withinthe lens barrel 20 a from a front portion of an imaging tip unit 12, onthe light-receiving surface 3 a of the imaging unit 3 in the solid-stateimaging element 4.

The outer frame member 21 is bonded and secured to the insulating tube15 of the imaging module 100 with outer layer resin 23 that fills theinside of the outer frame member and is cured.

The insulating tube 15 prevents the conductor connecting portion 17 aand the conductor connecting portion 17 b, which are respectively formedin the two rear pieces 12 and 13 of the flexible wiring substrate 10,from contacting the outer frame member 21 to cause short-circuiting.

The flexible wiring substrate 10 of the imaging module 100 will befurther described.

As shown in FIGS. 1 and 2A, the rear pieces 12 and 13 of the flexiblewiring substrate 10 have extending portions 12 e and 13 e that are bentwith respect to the element mounting portion 11, and connecting pieces12 f and 13 f that extend from extending ends 12 e 1 and 13 e 1 of theextending portions 12 e and 13 e to the rear portion.

As shown in FIG. 2A, the extending portions 12 e and 13 e have extendingbase portions 12 g and 13 g and inclined extending portions 12 h and 13h.

In FIG. 2A, the extending base portions 12 g and 13 g extend from boththe end portions (both the end portions of the substrate in thelongitudinal direction D1 (upward-downward direction in FIG. 1)) of theelement mounting portion 11 to the rear portion. The extending baseportions 12 g and 13 g are substantially perpendicular to the elementmounting portion 11.

The inclined extending portions 12 h and 13 h extend from extending ends12 g 1 and 13 g 1 of the extending base portions 12 g and 13 g so as toapproach each other as inclined extending portions are separated fromthe element mounting portion 11. The inclined extending portions 12 hand 13 h abut against each other in the extending ends 12 e 1 and 13 e1.

As shown in FIG. 1, the connecting piece portions 12 f and 13 fconstitute a substrate mating portion 24 in which facing surfaces 12 aand 13 a are made to abut against each other.

In the substrate mating portion 24, the connecting pieces 12 f and 13 fare bonded together with interlayer resin 24 a interposed between thefacing surfaces 12 a and 13 a.

A substrate internal space 25, having a home base shape, which aresurrounded by the extending portions 12 e and 13 e, the element mountingportion 11, and the substrate mating portion 24 is filled with adhesiveresin R. The extending portions 12 e and 13 e and the element mountingportion 11 are bonded and secured to each other with the adhesive resinR.

In the flexible wiring substrate 10, the shape of a portion locatedaround the substrate internal space 25 is constrained with the adhesiveresin R that fills the substrate internal space 25 and is cured, and isnot easily deformed, and shape stability is guaranteed.

That is, in the flexible wiring substrate 10, the shape of a tip portion18 (a portion consisting of the element mounting portion 11 and theextending portions 12 e and 13 e) of the flexible wiring substrate 10can be stably maintained with the adhesive resin R that is buried andcured in the substrate internal space 25.

It is preferable that the elastic modulus of the insulated base material10 a constituting the flexible wiring substrate 10 be 6 GPa or less, andit is preferable that the elastic modulus of the wiring 14 constitutingthe flexible wiring substrate 10 similar to the insulated base material10 a be 35 GPa or less.

Next, the substrate internal space 25 formed between the elementmounting portion 11 and the rear pieces 12 and 13 of the flexible wiringsubstrate 10 and the adhesive resin R, which fills the substrateinternal space 25, will be described below with reference to FIGS. 1 to3.

As shown in FIGS. 1 to 2B, the adhesive resin R with which the substrateinternal space 25 of the flexible wiring substrate 10 is filled isformed in a pentagonal shape (or a substantially pentagonal shape)(designated by reference sign 30) as a whole by the element mountingportion 11 and the rear pieces 12 and 13.

As shown in FIGS. 2A to 3, it is preferable that an outside dimension L1of the flexible wiring substrate 10 surrounding the adhesive resin R beequal to or less than an outside dimension L2 of the solid-state imagingelement 4 in the direction D1. It is preferable that the outsidedimension L1 be smaller than the outside dimension L2. The outsidedimensions L1 and L2 are the dimensions of the flexible wiring substrate10 in the longitudinal direction D1 in the element mounting portion 11.

In FIG. 3, the outermost periphery (a right-end portion in FIG. 3) ofthe flexible wiring substrate 10 in the direction D1 is located on aninner side in the direction D1, compared to the outermost periphery (theright-end portion of FIG. 3) of the solid-state imaging element 4 in thedirection D1.

It is preferable that the distance (designated by reference sign A1) inthe direction D1 between the outermost periphery (the right-end portionof FIG. 3) of the flexible wiring substrate 10 in the direction D1 andthe outermost periphery (the right-end portion of FIG. 3) of thesolid-state imaging element 4 in the direction D1 be 0 mm to 0.195 mm.

It is preferable that an inside radius (designated by reference sign A2in FIG. 3) of a bent portion 10A of the flexible wiring substrate 10 be0.05 mm to 0.10 mm. By setting an inside radius A2 to this range, thediameter of the tip portion 18 can be made small, and disconnection inthe bent portion 10A can be prevented.

It is, preferable that the distance (designated by reference sign A3 inFIG. 3) in the direction D1 from the outermost periphery (a right end ofFIG. 3) of the bump 4 a on the flexible wiring substrate 10 on which thesolid-state imaging element 4 be mounted to the innermost periphery ofthe bent portion 10A in the direction D1 be 0 mm to 0.195 mm. By settingthe distance A3 to this range, the diameter of the tip portion 18 can bemade small.

It is preferable that the distance (designated by reference sign A4 inFIG. 3) in the direction D1 between the outermost periphery (the rightend of FIG. 3) of the bump 4 a on the flexible wiring substrate 10 onwhich the solid-state imaging element 4 is mounted and the outermostperiphery (right-end portion of FIG. 3) of the solid-state imagingelement 4 in the direction D1 be 0 mm to 0.195 mm. By setting thedistance A4 to this range, the strength of joining between the elementmounting portion 11 and the solid-state imaging element 4 can beenhanced.

When the internal diameter (designated by reference sign A2 in FIG. 3)of the bent portion 10A of the flexible wiring substrate 10 is set to be0.05 mm to 0.10 mm, it is preferable to select a flexible material withan elastic modulus of 1.5 GPa or less and a breaking elongation of 30%or more for the resist film 10 b (refer to FIG. 2A) located on anoutside surface of the flexible wiring substrate 10. In addition, theelastic modulus of general resist for flexible wiring substrates is 3GPa or more, and the breaking elongation is approximately severalpercents.

The reason why the inside bending radius of the bent portion 10A is 0.10mm or less is because the bent portion 10A reaches the outer side beyondthe outside dimensions of the solid-state imaging element 4 if thebending radius exceeds 0.10 mm.

Meanwhile, in the elastic modulus and the breaking elongation of theabove-described general resist for flexible wiring substrates, there isa concern that the resist surface may break when the inside bendingradius of the bent portion 10A is 0.10 mm or less.

Thus, breaking of a resist surface can be avoided by selecting materialswith an elastic modulus of 1.5 GPa or less and a breaking elongation of30% or more and setting the inside bending radius of the bent portion10A to 0.05 mm or more in order to form the resist film 10 b located onthe outside surface of the flexible wiring substrate 10.

Additionally, if the inside bending radius of the bent portion 10A isless than 0.05 mm, breaking of the resist surface is apt to occur evenif any kinds of material are used as a resist film 10 b.

The resist film 10 b for flexible wiring substrates is not anindispensable constituent element. The resist film may be omitted ifnecessary for prevention of an increase in the diameter of the flexiblewiring substrate 10 as long as short circuiting does not occurs withrespect to the outer frame member 21.

FIG. 5 is a sectional view showing a portion of a tip portion of animaging module in which the flexible wiring substrate 10 does not havethe resist film 10 b.

As shown in FIGS. 2A and 2B, the adhesive resin R with which thesubstrate internal space 25 of the flexible wiring substrate 10 isfilled is formed in a pentagonal shape 30 having five corners (theangles of the respective corners are defined as θ1 to θ5) indicated byreference signs r1 to r5. Sides of the pentagonal shape 30 arerespectively designated by reference signs 30A to 30E.

The corner r1 (first corner) and the corner r5 (second corner) of theadhesive resin R, as shown in FIGS. 2A and 2B, are corners between theelement mounting portion 11 and the rear pieces 12 and 13. It ispreferable that the angles θ1 and θ5 of the corners r1 and r5 be 90° ormore. It is preferable that the corners r1 and r5 have a curved convexsurface 26.

The corner r2 (intermediate corner) and the corner r4 (intermediatecorner) are corners between the extending base portions 12 g and 13 gand the inclined extending portions 12 h and 13 h. It is preferable thatthe angles θ2 and θ4 of the corners r2 and r4 be 90° or more and lessthan 180°.

The corner r3 (third corner) is a corner formed in a place where the twoinclined extending portions 12 h and 13 h are joined together.

In the shown example, the angles θ1 and θ5 of the corners r1 and r5 areapproximately 90°, and the adhesive resin R forms a home base-likepentagonal shape 30 as a whole.

In addition, the shape of the adhesive resin R shown in FIGS. 1 to 2B isan example, and the shape of the adhesive resin R is not limited tothis. For example, as shown in FIG. 4A, the angles θ1 and θ5 of thecorners r1 and r5 may be larger than 90°. Additionally, as shown in FIG.4B, the adhesive resin R may be formed in a polygonal shape exceeding apentagonal shape. The adhesive resin R shown in FIG. 4B is a heptagonthat has a corner r6 between the corner r2 and r3 and has a corner r7between the corner r3 and r4. Additionally, as shown in FIG. 4C, a sidebetween the corner r1 and the corner r3, and a side between the cornerr5 and the corner r3 may be a curved convex shape.

Next, the adhesive resin R with which the substrate internal space 25 ofthe flexible wiring substrate 10 is filled will be described.

As the adhesive resin R, a resin in which a glass-transition temperatureis 135° C. or less is used. As the adhesive resin R, for example,UV-curable acrylic resin or epoxy-based resin is suitably used.Accordingly, the adhesive resin R can be softened when the imagingmodule 100 is put in a high-temperature state (approximately 135° C. ormore) in sterilization processing using an autoclave.

In addition to a glass transition temperature being 135° C. or less,materials for the adhesive resin R may also be selected taking a rate ofvolumetric shrinkage of the resin in curing into consideration.

For example, as the adhesive resin R, adhesive resin in which the rateof volumetric shrinkage is 3% or more is preferably used. Thus, in amanufacturing process to be described below, when a reference pin 50 ispulled out and the substrate internal space 25 is filled with theadhesive resin R and this adhesive resin is cured, the extendingportions 12 e and 13 e are pulled inward with the shrinkage force of theadhesive resin R (refer to the arrow of FIG. 2A), so that the extendingportions 12 e and 13 e can be inhibited from widening outward due to therestoring force of the flexible wiring substrate 10. Hence, the diameterof the tip portion 18 can be made smaller.

Since more contraction can be caused by the adhesive resin R if therates of volumetric shrinkage are 5% or more and 10% or more, thediameter of the tip portion 18 can be made smaller.

In addition, as the UV-curable acrylic resin suitably used as theadhesive resin R, for example, there are those having properties inwhich the glass transition temperature is 106° C. and the rate ofvolumetric shrinkage in curing becomes 12.8%.

The imaging module 100 is manufactured, for example, as shown in FIGS.6A to 6E.

First, as shown in FIG. 6A, a pentagonal reference pin 50 is arranged onthe mounting part back surface 11 b of the flexible wiring substrate 10.The reference pin 50 brings a portion corresponding to a side 30A (referto FIG. 2A) of the pentagonal shape 30 into close contact with themounting part back surface 11 b of the flexible wiring substrate 10.

The surface of the solid-state imaging element 4 installed on themounting surface 11 a of the flexible wiring substrate 10 is held downfrom above.

The outer shape of the reference pin 50 is appropriately selected tocorrespond to the shape of the adhesive resin R to be finally formed(refer to FIGS. 2A to 4C).

As shown in FIG. 6B, the extending portions 12 e and 13 e (extendingbase portions 12 g and 13 g) are formed by bending both the end portionsof the element mounting portion 11 of the flexible wiring substrate 10.

As shown in FIG. 6C, an adhesive 53 is coated on an inner surface of alocation that becomes a connecting piece 13 f of a rear piece 13 of theflexible wiring substrate 10.

As shown in FIG. 6D, the connecting pieces 12 f and 13 f of the flexiblewiring substrate 10 are bonded together with an adhesive 53. This formsthe substrate mating portion 24 of the flexible wiring substrate 10.

As shown in FIG. 6E, the adhesive resin R is cured after the referencepin 50 inserted between the element mounting portion 11 and the rearpieces 12 and 13 of the flexible wiring substrate 10 is pulled out andthe substrate internal space 25 in which the reference pin 50 isarranged is filled with the adhesive resin. R.

In the imaging module 100, a substrate internal space 25 of the flexiblewiring substrate 10 surrounded by the element mounting portion 11 andthe two rear pieces 12, 13 is filled with adhesive resin R in which aglass-transition temperature is 135° C. or less. Therefore, the adhesiveresin R can be softened when being put in a high-temperature state (forexample, 135° C. or more) in sterilization processing using anautoclave.

Accordingly, a situation in which a large force is applied to the bentportion 10A or the like of the flexible wiring substrate 10 can beavoided even in a high-temperature state, and damage of the flexiblewiring substrate 10 can be prevented. As a result, connectionreliability can be improved.

Additionally, since no large force is applied to the flexible wiringsubstrate 10 by the adhesive resin R, an excessive force is not appliedto the bent portion 10A even if the outside dimensions of the flexiblewiring substrate 10 surrounding the adhesive resin R are made small.Hence, the diameter of the imaging module 100 can be reduced byadjusting the shape of the flexible wiring substrate 10 surrounding theadhesive resin R.

Since the imaging module 100 has a configuration in which the substrateinternal space 25 of the flexible wiring substrate 10 is filled with theadhesive resin R, a member for maintaining the shape of the flexiblewiring substrate 10 is unnecessary, and disconnection of the flexiblewiring substrate 10 caused by a difference in coefficient of thermalexpansion from that of the member does not occur.

In the imaging module 100, since the adhesive resin R which is softenedin a high-temperature state is used, the adhesive resin R has a shapeaccording to the shape of the flexible wiring substrate 10. Therefore,the alignment between the adhesive resin R and the flexible wiringsubstrate 10 is not necessary, and manufacture is easy.

In contrast, when the member for maintaining the shape of the flexiblewiring, substrate 10 is used, since the alignment between the member andthe flexible wiring substrate is required, substantial time and effortare required for manufacture. Additionally, since the member requiresprecision processing, high-volume manufacture is difficult, and costsincrease.

Although the embodiment of the present invention has been describedabove in detail with reference to the drawings, the specificconfiguration is not limited to the embodiment, and design changes orthe like are also included without departing from the scope of thepresent invention. For example, the extending portions are not limitedto the shown structure as long as they have the structure in whichportions including at least the extending ends approach each other asthey move away from the element mounting portion.

Moreover, additions, omissions, substitutions, and other modificationscan be made without departing from the spirit or scope of the presentinvention. Accordingly, the invention is not to be considered as beinglimited by the foregoing description, and is only limited by the scopeof the appended claims.

What is claimed is:
 1. An imaging module comprising: an electricalcable; a solid-state imaging element comprising an imaging unitorthogonal to an axis direction of a tip of the electrical cable; and aflexible wiring substrate in which the solid-state imaging element andthe electrical cable are electrically connected together, wherein theflexible wiring substrate comprises an element mounting portion mountingthe solid-state imaging element, a first rear piece that is bent at afirst end of the element mounting portion and extends in a directionaway from the element mounting portion, and a second rear piece that isbent at a second end opposite to the first end and extends in adirection away from the element mounting portion, wherein the first rearpiece comprises a first extending base portion, which extends directlyfrom the first end and is perpendicular to the element mounting portionthat extends from the first extending base portion, and a first inclinedextending portion, and the second rear piece comprises a secondextending base portion, which extends directly from the second end andis perpendicular to the element mounting portion, and a second inclinedextending portion that extends from the second extending base portion,wherein the first inclined extending portion and the second inclinedextending portion are configured so that portions, which comprise atleast a first extending end of the first inclined extending portion andthe second extending end of the second inclined extending portion,approach each other as the first and second inclined extending portionsare away from the element mounting portion, and wherein an internalspace of the flexible wiring substrate surrounded by the elementmounting portion, the first extending base portion, the first inclinedextending portion, the second extending base portion, and the secondinclined extending portion is filled with an adhesive resin in which aglass-transition temperature is 135° C. or less.
 2. The imaging moduleaccording to claim 1, wherein the first and second rear pieces furthercomprise connecting pieces further extending from ones of the firstextending end and the second extending end.
 3. The imaging moduleaccording to claim 1, wherein the outside dimensions of the flexiblewiring substrate comprising the element mounting portion and the firstand second rear pieces, which cover the adhesive resin, are equal to orless than the outside dimensions of the solid-state imaging element. 4.The imaging module according to claim 1, wherein the adhesive resin isan acrylic resin or an epoxy-based resin.
 5. The imaging moduleaccording to claim 1, wherein the adhesive resin has intermediatecorners between first, second corners, which are formed between theelement mounting portion and the two extending base portions, and athird corner formed in a place where the two inclined extending portionsmeet, respectively, and is formed in a polygonal shape having five ormore sides as a whole.
 6. The imaging module according to claim 1,wherein a rate of volumetric shrinkage in curing of the adhesive resinis 3% or more.
 7. A catheter comprising: the imaging module according toclaim 1.